1. Field of the Invention
This invention relates generally to mechanical drive arrangements, and more particularly, to a high capacity press system that is driven in response to actuation of a ballscrew drive that is coupled to a platen of the press via gimbals, universal joints, end rods, or any other system that is suitable for accommodating canting of the platen or other transaxial motion.
2. Description of the Related Art
Conventional high capacity press systems, such as those that are employed in the motor vehicle manufacturing industry to stamp and hem sheet metal body panels and doors, employ stationary and translatable stamping portions, the translatable stamping portion generally being guided along a predetermined path of travel. In some known arrangements, a generally rectangular translatable stamping portion is provided with a guidance arrangement having four guide posts on which are slidably engaged respective guide bushings that are coupled to the translatable stamping portion. The displacement of the translatable stamping portion is responsive to a hydraulic or electromechanical drive arrangement that urges the translatable stamping portion toward the stationary stamping portion with great force. In press systems that are employed in the manufacture and hemming of vehicle body panels, forces on the order of several hundred tons are applied to the product interposed between the translatable stamping portion and the stationary stamping portion.
It is a problem with conventional high capacity electro-mechanical press systems that catastrophic failure of the platen drive arrangement, particularly when the platen drive has incorporated therein a ballscrew system, will result from high offset forces and bending moments. Such compression forces are particularly severe when safety systems of the press, such as limit switches, fail or when hand tools or other foreign objects are inadvertently left on the stationary die bed, and generally will result in crash load forces of magnitudes that damage the platen drive arrangement.
It is another problem with conventional high capacity electro-mechanical press systems that excessive wear causes a reduction in the operating interval between overhauls to well under one million operating cycles. On the other hand, conventional hydraulic high capacity press systems require extended cycling times and frequent maintenance schedules due to leakage.
It is, therefore, an object of this invention to provide a high capacity press system that is less likely to suffer catastrophic failure resulting from excessive offset forces and bending moments to the platen when a foreign object, such as a hand tool, is compressed after inadvertently being left between press dies.
It is also an object of this invention to provide a high capacity press system that has a greater interval between major overhauls.
It is another object of this invention to provide a high capacity press system that has a reduced cycling time, thereby achieving greater throughput.
It is a still further object of this invention to provide a high capacity press system that controls or limits the crash force applied to the platen drive arrangement.